This being STW you’ll probably told that you really should be getting some rollers 🙂
Just get a turbo that looks like it’s got a decent stable base. The old tacx ones were good. A wide range of variable resistance can be useful depending on what sort of workouts you want to do. Also one that’s easy to get the bike in and out of can be useful if you need to swap bikes. Oh and get a turbo specific tyre.
Well worth looking at trainerroad.com too if you have that setup.
Edit: this buyers guide on road.cc might help. A lot of people seem to rate the Kurt Kinetic ones.